Patent GB-532096-A (GB)
Title: Improvements in or relating to automatic train control systems
IPC: B61L3/12
Filed: 1939-04-05
Abstract: 532,096. Cab-signal and train control systems. SIEMENS & GENERAL ELECTRIC RAILWAY SIGNAL CO., Ltd., AUSTIN, T., and MOTT, J. E. April 5, 1939, No. 10637. [Class 105] In train control apparatus in which signalling and braking means on the train are operated by magnetic means on the track, the receiving means on the train includes a relay comprising two magnetized armatures 1, 2, Fig. 1, pivoted on horizontal shafts 3, 4 disposed between upper and lower normally unmagnetized pole-pieces 5, 6, 7, 8 which are spaced to allow limited rocking movement to members 1, 2 to control contacts, not shown in Fig. 1. Normally, members 1, 2 are disposed with ends of similar polarity respectively in contact with the upper and lower pole-pieces, as. shown. The track apparatus includes a magnet adapted to exert unipolar influence on the relay, to operate members 1, 2 selectively. Thus, as shown, passage over a track device of north polarity rocks member 1 clockwise but leaves member 2 unaffected, whilst passage over a south pole track device operates member 2 but not member 1. The track magnet may be permanent with means for shrouding one of the poles, or may be an electromagnet which can be energized in either direction. A magnet with both poles unshrouded may be used, in which case the pole last passed over exerts the effective unipolar influence. Fig. 2 shows resetting means comprising arms 9, 10 on the shafts 3, 4, and a magnet 12 with a movable armature 11 which, when attracted, rocks the shafts to restore them to the position shown in Fig. 1. Figs. 3, 4 illustrate an application to the control of brakes on the train, the signalling arrangements not being illustrated. A permanent magnet 13 and electromagnet 16 with poles oppositely disposed as shown are situated between the track rails and co-operate with a single armature relay, for example of the kind described in Specification 407,382. A magnet 14 disposed at the side of the track and, for example, thirty yards ahead of magnet 13, co-operates in unipolar manner with the receiver of Fig. 1, its circuit including a reversing switch 15. Electromagnetic valves 17, 18 giving full and half braking respectively are controlled by relays 21, 22 bridged by condensers 25, 26 to give slow release of their contacts 19, 20. On passage of a locomotive over magnet 13 contact 23 is operated by the single-armature relay to break the circuits of relays 21, 22 and sound an alarm whistle or buzzer. Magnets 14, 16 are reached before the relay contacts 19, 20 release. If; as under danger conditions, both electromagnets are de-energized, contact 23 remains reversed and relays 21, 22 ultimately release their contacts and apply the brakes fully. If, as with the succeeding signal at danger, magnet 14 is energized to give effective north polarity, armature 1 operates contacts to give a yellow (Y) signal in the cab, full braking being applied. If, as when the succeeding signal is of yellow aspect, magnet 14 gives effective south polarity, armature 2 is operated to close contact 24, re-energizing relay 21 and preventing release of valve 17. Valve 18, however, releases, and half braking is applied. Under "clear" conditions, magnet 14 is de-energized and magnet 16 is energized. The single-armature relay and contact 23, after operation by magnet 13, are restored by magnet 16, so that relays 21, 22 remain energized and no braking occurs. At the same time a green signal is given in the cab and the alarm switched off. The Specification describes the use of the invention to allow for the difference in braking distances between steam and electric trains, and to give a multiplicity of indications by the use of a plurality of unipole devices.